Mechanism of the sperm acrosome reaction

描述（由申请人提供）：受精发生在精子顶体反应完成后，这是配子粘附过程中触发的分泌事件。在哺乳动物中，卵细胞分泌是由卵细胞外基质或透明带（ZP）的糖蛋白成分ZP3触发的。本项目的长期目标是了解顶体反应过程中ZP3信号转导的机制。我们之前已经证明瞬时受体电位规范（TRPC）通道在zp3诱导的小鼠精子顶体反应中起重要作用。本研究计划重点研究参与ZP3信号起始下游事件的trpc效应蛋白。利用酵母- 2杂交，我们发现了一种新的精子蛋白enkurin，它可以结合TRPC通道和磷脂酰肌醇-3-磷酸（PI3K）。enkurin- PI3K相互作用的证明促使我们研究PI3K在顶体反应中的作用。我们提供的初步数据表明，ZP3刺激PI3K产物磷脂酰肌醇-3,4,5-三磷酸（PIP3）的产生。PIP3是驱动顶体反应所必需的。有两个具体目的：1)产生雄性种系enkurin零小鼠，以确定enkurin在精子中的功能；2)确定zp诱导小鼠精子AR过程中PI3K的下游效应物；初步数据表明，AKT参与小鼠精子中zp -顶体反应信号通路。下一步是在顶体胞吐过程中确定这种激酶的底物。

DESCRIPTION (provided by applicant): Fertilization occurs after completion of the sperm acrosome reaction, a secretory event that is triggered during gamete adhesion. In mammals, secretion is triggered by ZP3, a glycoprotein component of the egg's extracellular matrix, or zona pellucida (ZP). The long range goal of this project is to understand the mechanism of ZP3 signal transduction during the acrosome reaction. We have previously shown that transient receptor potential canonical (TRPC) channels play an essential role in ZP3-induced acrosome reaction in mouse sperm. This research proposal focuses on TRPC-effector proteins that participate in events downstream of ZP3 signal initiation. Using a yeast-two hybrid we have identified a novel sperm protein, enkurin, which binds to both TRPC channels and phosphatidylinositol-3-phosphate (PI3K). The demonstration of an enkurin- PI3K interaction prompted us to investigate a role for PI3K in the acrosome reaction. We present preliminary data showing that ZP3 stimulates the production of the PI3K product phosphatidylinositol-3,4,5-triphosphate (PIP3). PIP3 is required to drive the acrosome reaction. There are two specific aims: 1) A male germline enkurin null mouse will be generated to determine the function of enkurin function in sperm; and 2) Identify downstream effectors of PI3K during the ZP-induced AR in mouse sperm; preliminary data suggests that AKT is involved in the ZP-acrosome reaction signaling pathway in mouse sperm. The next step is to identify the substrates of this kinase during acrosomal exocytosis. PROJECT NARRATIVE: Health problems are posed when fertilization is either unbounded or impeded. In this regard, the acrosome reaction is an important regulatory event during mammalian gamete interaction, with unregulated exocytosis associated with failure of fertilization. These studies define downstream effector proteins that are essential components of the ZP3 signaling pathway and may provide new targets for the control of fertilization.